Studies dig into physicians' views on vaccine issues

Oct 20, 2011 (CIDRAP News) – Survey results presented at a medical conference today suggest that younger doctors may be a little more skeptical about vaccines than their older counterparts are, but that most pediatricians work to overcome parental reluctance to have their children vaccinated.

Researchers who conducted studies on the two topics previewed their findings at a press briefing today at the Infectious Diseases Society of America (IDSA) meeting in Boston. They will present their findings tomorrow during poster sessions.

Looking for age-related differencesIn the first study, Saad Omer, PhD, MPH, MBBS, assistant professor of global health, epidemiology, and pediatrics at Emory University in Atlanta, and his colleagues wondered if a "cohort effect" found in parents who grew up in an age when they did not encounter vaccine-preventable diseases plays any role in the vaccine beliefs of healthcare providers.

Some experts have suggested that the cohort effect might be one factor behind the increasing numbers of parents who decline vaccinations for their children. Also, a now discredited and retracted 1998 study in TheLancet by Dr. Andrew Wakefield linked autism to the measles, mumps, and rubella vaccine (MMR), triggering a decline in MMR vaccine uptake in many countries, along with a widespread belief that the vaccine causes autism.

"What we wanted to see is, can the effect be seen in physicians, as well? For providers who have seen a case of whooping cough or treated meningitis, that experience is a little more visceral," Omer said.

Omer's group conducted a cross-sectional survey in 2005 of primary care providers identified by parents of children who were fully vaccinated, as well as those who were exempt from one or more school immunization requirements.

The survey, completed by 551 providers with an 84.3% response rate, questioned doctors about their beliefs on immunization, disease susceptibility, vaccine safety, and vaccine efficacy. Researchers stratified the responses based on year of graduation from medical school and calculated the odds ratios for each 5-year cohort regarding their vaccine beliefs.

They found that younger doctors were more likely to believe that immunizations do more harm than good. Also, the more recent graduates were 15% less likely to believe vaccines were effective, compared with older ones.

Younger doctors were also less likely to believe that inactivated polio, oral polio, MMR, and varicella vaccines were safe, Omer said. He added that perceptions didn't seem to be swayed by how long the vaccine had been on the market, though it appeared that younger physicians were more skeptical about live attenuated vaccines.

The main take-home message from the study is that overall physician support for vaccines remains high, but there may be a subtle but statistically significant cohort effect in younger doctors that is more pronounced for vaccine efficacy and safety. The study found no difference between younger and older physicians' beliefs about disease susceptibility and severity.

Responding to vaccine hesitancyThe second study explored how much of a problem vaccine hesitancy is in pediatric practices and how physicians approach the situation. Findings were presented by two members of the research team: Chris Harrison, MD, director of the Infectious Disease Research Laboratory at Children's Mercy Hospitals and Clinics in Kansas City, Mo., and Tom Tryon, MD, section chief at Children's Mercy Northland Urgent Care Center, also in Kansas City.

The team conducted an online survey among physicians in nine Midwestern states that are part of the American Academy of Pediatrics' sixth district. They asked physicians which vaccines parents most often refuse, the reasons for refusal, and how they handle parents who refuse the vaccines for their children. The survey drew 909 responses, 695 of them complete, for a response rate of about 20%, Tryon said.

The three vaccines parents were most likely to decline were MMR, human papillomavirus, and influenza, according to the researchers. The most common reasons were fears of autism, concerns about too many shots, and worries about serious side effects.

When parents expressed hesitancy about vaccines, the top physician response was engaging the family in discussions about vaccines and presenting options. Two-thirds of the survey respondents said they referred families to evidence-based Web sites, and nearly as many used evidence-based literature to help educate parents.

Clinician reports of the proportion of parents in their practices who refuse or want to modify vaccinations varied, with 0% to 40% refusing vaccination and 1% to more than 50% requesting a delay or modification of the vaccine schedule, the group reported. Nationally, the level of vaccine refusal is less than 5%, they added.

They found that 21% of physicians discharge families for persistently refusing vaccines, with levels that varied by state, from 0.9% in Minnesota to 38% in Iowa.

Harrison told reporters that the number of physicians in the survey who engaged families in discussions was high at 95%. "Pediatricians are taking personal ownership of the counseling," he said.

On the other hand, the percentage of physicians who would discharge a family for refusing childhood vaccines shows that the topic is a hot-button issue for physicians, he said. "They're likely to need some more support in handling these issues," he said.

Tryon said the study shows that physicians have different perceptions about how unvaccinated children might pose a risk to others they come into contact with in doctors' waiting rooms. He said the fairly wide variation in responses on the issue by physicians in different states might reflect demographic or cultural differences. He added that the level of tolerance didn't seem to relate to state childhood vaccine uptake levels.